Recurring urinary tract infection in male?

Hey everyone, I'm in a situation with my long term boyfriend and I really don't know where to go to for help before ending things with him. To make a long story short, he recently told me that he keeps getting recurring urinary tract infections every time we have sex. It's gotten to the point where we've hardly had sex in the past two years.

He's gone to regular doctors and all they've told him is that his "immune system must not be able to handle other people's bodies" and to just "wear a condom." This sounds like complete rubbish to me. Condoms kill intimacy, in my opinion, and they have a long list of chemicals in them that I don't want anywhere near my body.

With that being said, if someone is getting UTIs all the time there's clearly a deeper issue. He's 25, somewhat overweight but not obese, and isn't really a healthy eater.

I, personally, was able to cure my UTI with apple cider vinegar and baking soda. He doesn't seem to believe this.

Any of you guys have any idea what might be causing his chronic UTIs and what we can do to try to prevent them from happening so we can have a normal relationship and sex life again? Thank you guys so much!!